Light detection device, method of manufacturing light detection device, and electronic equipment

Abstract

A light detection device capable of suppressing the worsening of noise characteristics is provided. The light detection device includes a semiconductor layer having photoelectric conversion regions, one surface of the semiconductor layer forming a light incident surface, the other surface of the semiconductor layer forming an element forming surface, a trench positioned to partition the photoelectric conversion regions and penetrating the semiconductor layer in a direction of thickness thereof, and a separation part formed in the trench and including a first separation part and a second separation part, the first separation part being positioned on the side of the light incident surface, the second separation part being positioned on the side of the element forming surface. A first surface of the second separation part on the side of the first separation part faces a first material.

What is claimed is: 
     
         1 . A light detection device, comprising:
 a semiconductor layer having photoelectric conversion regions, one surface of the semiconductor layer forming a light incident surface, another surface of the semiconductor layer forming an element forming surface;   a trench positioned to partition the photoelectric conversion regions and penetrating the semiconductor layer in a direction of thickness thereof; and   a separation part formed in the trench and including a first separation part and a second separation part, the first separation part being positioned on a side of the light incident surface, the second separation part being positioned on a side of the element forming surface,   wherein a first surface of the second separation part on a side of the first separation part faces a first material.   
     
     
         2 . The light detection device according to  claim 1 , wherein the first material includes silicon nitride. 
     
     
         3 . The light detection device according to  claim 1 , wherein the first material includes a material resistant to hydrogen fluoride. 
     
     
         4 . The light detection device according to  claim 1 , wherein the first material includes either titanium nitride or tungsten. 
     
     
         5 . The light detection device according to  claim 1 , wherein the first material includes any one of polysilicon, silicon oxide, hafnium oxide, and aluminum oxide. 
     
     
         6 . The light detection device according to  claim 1 , wherein the first material includes silicon doped with impurities. 
     
     
         7 . The light detection device according to  claim 6 ,
 wherein the impurities include boron, and   the first material includes silicon doped with boron at a concentration of 5×10 18  atoms/cm 3  or higher.   
     
     
         8 . The light detection device according to  claim 6 , wherein the impurities include boron and carbon. 
     
     
         9 . The light detection device according to  claim 1 , wherein the second separation part includes the first material. 
     
     
         10 . The light detection device according to  claim 1 , wherein the second separation part has a multilayer structure in which a first layer including the first material and constituting the first surface and a second layer including a second material different from the first material are stacked. 
     
     
         11 . The light detection device according to  claim 10 ,
 wherein the second separation part has a horizontal size greater than that of the first separation part, and   the first layer is formed in a region where there is an overlap at least with the first separation part in the thickness direction.   
     
     
         12 . The light detection device according to  claim 1 , wherein a distance between the first surface of the second separation part and the element forming surface is from 200 nm to 300 nm inclusive. 
     
     
         13 . The light detection device according to  claim 1 , wherein the first material includes a material that suppresses etching of the second separation part. 
     
     
         14 . The light detection device according to  claim 1 , comprising:
 a fixed charge film,   wherein the fixed charge film is interposed at least between the first separation part and the second separation part.   
     
     
         15 . The light detection device according to  claim 14 , further comprising:
 a silicon oxide film interposed between the second separation part and the fixed charge film.   
     
     
         16 . The light detection device according to  claim 10 , wherein the second material includes an insulating material. 
     
     
         17 . The light detection device according to  claim 10 , wherein the second material includes a conductive material. 
     
     
         18 . The light detection device according to  claim 1 , wherein, of a portion including silicon oxide and a portion including metal, the first separation part includes at least the portion including silicon oxide. 
     
     
         19 . A method of manufacturing a light detection device, comprising:
 forming a trench in a position to partition photoelectric conversion regions in a semiconductor layer from a side of an element forming surface thereof;   stacking, in the trench, a sacrificial layer and a first material in this order in a direction of thickness of the semiconductor layer, the first material being a material of which an etching rate relative to a selected etchant is lower than that of a material constituting the sacrificial layer;   exposing the sacrificial layer from a side of a light incident surface opposite to the side of the element forming surface;   removing the sacrificial layer while leaving the first material intact, by use of the selected etchant; and   embedding a material different from the material of the sacrificial layer into the trench from the side of the light incident surface.   
     
     
         20 . Electronic equipment, comprising:
 a light detection device; and   an optical system that causes the light detection device to form an image of image light from a subject,   wherein the light detection device includes
 a semiconductor layer having photoelectric conversion regions, one surface of the semiconductor layer forming a light incident surface, another surface of the semiconductor layer forming an element forming surface, 
 a trench positioned to partition the photoelectric conversion regions and penetrating the semiconductor layer in a direction of thickness thereof, and 
 a separation part formed in the trench and including a first separation part and a second separation part, the first separation part being positioned on a side of the light incident surface, the second separation part being positioned on a side of the element forming surface, and 
   a first surface of the second separation part on a side of the first separation part faces a first material.